DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



171 



region is only slightly higher than the frontal. The temporal 

 fossae are not deeply excavated, and the occipital crests are 

 weakly developed when compared to this region of the slcull in 

 Limnohyops. The occiput itself is high and rather narrow. 

 The foramen magnum is wide, bordered by very large condyles. 

 The auditory processes are widely separated. The post- 

 tympanics are broad and heavy. The postglenoid is peculiar 

 in form; it is very short and thick; its form is very different 

 from other species in the collection. An internal glenoid 

 process is present in this species. The mastoid was probably 

 exposed. The form of the zygomatic arch is striking; it is 

 very light, nearly straight, with the temporal portion strongly 

 compressed. The malar portion is also peculiar; the malar 

 insertion is very abrupt and strongly depressed, With the 

 external part very broad, thin, and shelf-like. The infra- 

 orbital foramen is not exposed. The form of the malar in this 

 species is totally different from all other allied forms 

 that I have examined. The orbit is very small, termi- 

 nates anteriorly above the anterior border of the second 

 superior molar; the postorbital processes are well 

 marked. The facial region of the skull is very short, 

 compared to the total length of the cranium. The 

 nasals are very long and heavy; their distal portion is 

 expanded and broader than the middle part. The nasal 

 notches are very deep and high. The premaxillaries are 

 triangular in outline; their symphysis is short and nar- 

 row, with a prominent anterior keel. The canine al- 

 veolus is very prominent. The palate is long and nar- 

 row, the roof of the same being strongly arched. The 

 posterior termination of the palate is at the second 

 superior molar. The incisive foramina are not divided. 

 Teeth: The crowns of the teeth in this skull are 

 badly damaged, but enough remains to give the total 

 measurements and the characters of the last molar. 

 The superior molars in this species form a continuous 

 series, being not interrupted by a diastema. The 

 sections of the incisors are very small. The canines 

 are also very small and diverge widely. Only the 

 second and third molar of each side are partially pre- 

 served. They have a square form with low crowns; 

 externally they are totally without a cingulum. The 

 external V's are rather wide and angular, in this respect 

 approaching that of Telmalotherium. The last molar 

 is without any intermediate conules. 



Measurements 



Millimeters 

 Length of skull, from premaxillary symphysis to end 



postglenoid ' 285 



Length from orbit to premaxillary symphysis 125 



Length from orbit to postglenoid 160 



Depth of nasal notch 84 



Length of nasals 100 



Entire molar series 148 



Last superior molar: 



Anteroposterior 37 



Transverse 39 



Etymology. — fie-yas, great, pis, nose; in allusion to the 

 length of the nasal bones. 



Present determination. — This is a valid species which 

 has been made the type of the genus MesatirJiinus 

 by Osborn. (See p. 388.) 



Palaeosyops minor Earle, 1891 

 Cf. Palaeosyops paludosus, this monograph, page 319 



Original reference. — Acad. Nat. Sci. Philadelphia 

 Proc. for 1891, p. 112, issued March 31, 1891 (Earle, 

 1891.2). 



Subsequent reference. — Earle, A memoir upon the 

 genus Palaeosyops Leidy and its allies: Acad. Nat. 

 Sci. Philadelphia Jour., 2d ser., vol. 9, pp. 269, 331, 

 332, 1892 (1892.1). 



Earle's cotypes. — In his original description Earle 

 says (1891.2, p. 112), "P. minor embraces specimens 

 which Leidy erroneously described as P. paludosus, pi. 

 4, figs. 3-6, of Leidy's report for 1873." In his memoir 

 (1892.1, pp. 269, 330) Earle refers again to Leidy's 

 Plate 4, Figures 3-6, as the types of P. minor, but on 

 page 332 he says, "We may consider as the type 

 specimen" the "beautifully preserved mandible fig- 



FiGURB 106. — Type (holotype) of skull of Palaeosyops megarhinus 

 Princeton Mus. 10008. After Earle, 1892. No scale given. 



ured by Leidy" (Leidy, 1873.1, pi. 5, figs. 10, 11); 

 and again on page 387 he states that the specimen 

 figured in his (Earle's) Plate 12, Figure 14, is "the 

 type of this species and is in the collection of the 

 Academy of Natural Sciences of Philadelphia." But 

 this specimen is apparently the same one figured in 

 Leidy's Plate 4, Figure 5. (See fig. 107.) 

 Specific characters. — Earle writes: 



Second superior premolar with two external lobes, external 

 lobes of last superior premolar equal. Intermediate conules of 

 true molars reduced, a strong external cingulum present. 



Etymology. — minor, in allusion to the relatively 

 small size. 



Present determination. — Of the first-mentioned speci- 

 mens (Leidy, 1873.1, pi. 4, figs. 3-6) Figures 3 and 4 

 represent an upper dentition, which is probably con- 

 specific with P. paludosus as determined in this mono- 

 graph; hence if this is taken as Earle's type P. minor 

 becomes a synonym of P. paludosus. 



